Goods and other items may be tracked and identified using an RFID system. An RFID system includes at least one tag and a reader. The tag is a small transponder typically placed on an item to be tracked. The reader, sometimes referred to as an interrogator, includes a transceiver (alternatively, separate transmitter and receiver) and one or more antennas. The antennas emit electromagnetic (EM) waves generated by the transceiver, which, when received by tag, activates the tag. Once the tag activates, it communicates using radio waves back to the reader, thereby identifying the item to which it is attached.
There are three basic types of RFID tags. A beam-powered tag is a passive device which receives energy required for operation from EM waves generated by the reader. The beam powered tag rectifies an EM field and creates a change in reflectivity of the field which is reflected to and read by the reader. This is commonly referred to as continuous wave backscattering. A battery-powered semi-passive tag also receives and reflects EM waves from the reader; however a battery powers the tag independent of receiving power from the reader. An active tag, having an independent power supply, actively transmits EM waves which are then received by the reader.
Communication between the tag and reader is defined by an air interface communication protocol. For example, RFID tags can be implemented using (i) EPCglobal's Class 1 Generation 2 UHF Air Interface Protocol Standard Version 1.0.9: (“Gen 2”); or (ii) ISO/IEC 18000-6:2004 Information technology—Radio frequency identification for item management—Part 6: Parameters for air interface communications at 860 MHz to 960 MHz (type A, B, or C devices). These protocols are incorporated by reference herein.
However, the above protocols may not adequately address privacy and security concerns for certain RFID applications. For privacy, an RFID tag can be permanently disabled as described as one embodiment in U.S. Pat. No. 6,933,848, entitled “System and Method for Disabling Data on Radio Frequency Identification Tags,” assigned to Alien Technology Corporation, which is incorporated by reference herein. All of the efficiencies provided by RFID technology are lost with a permanently disabled tag. It would be advantageous for a tag to provide privacy, and yet continue to provide useful information (such as, a recycling identifier, hazardous waste information, or regulatory disposal requirements).
For security, a conventional tag can be locked, whereby individual memory banks cannot be read directly. In the supply chain, it may be prudent in some circumstances for a tag not to identify its associated item. For example, if the tag identifies a controlled pharmaceutical substance, one may want to conceal this fact during transport in the supply chain. But, if the tag's electronic product code (EPC) is inaccessible, the efficiencies provided by RFID technology are lost. A tag that affords security and continues to supply useful information (such as, a less specific EPC) is highly desirable.
The above protocols provide for reprogramming a tag with a new ID (“identifier”), however reprogramming a tag requires that the information to be programmed be available at the point where the ID is changed, and may require that many bits are programmed at the tag. For example, if it is desirable to replace an EPC with a recycle code, the best party to determine the proper recycle code may be the party that originally commissioned the tag, (programming it with its primary ID) rather than the retailer, consumer or other party who would decommission the tag from the supply chain and convert the tag into a recycle tag. If the recycle code or other recycle code is available in another memory segment of the tag, preexisting protocols would require that it be read out of the tag and then programmed into the ID memory of the tag, requiring multiple commands and taking substantial time.
From the above, it is seen that methods and apparatuses for “tiered” RFID devices having identifiers arranged in layers of an operating procedure, as described below, can provide many benefits.